with code like this
if(lmastery-dmastery>maxdif)
    maxdif = lmastery - dmastery;

i got WA 10

but with
if(lmastery-dmastery>maxdif+1e-9)
    maxdif = lmastery - dmastery;
i got AC

I havn't rools for choosing right value eps=1e-9.
Insread I use more 10 times already my unit
for long arithmetics and have Ac.
In this problem I used fraction of tipe LongA/longA.
Of couse authors used flouts but my exact arithm and
author's rounding floats correspond and it is very very
surprisingly.
Except for roudindg problem is very simple and
dosn't demand any optimization for time and memory.

Nice advice! Thank you.